Steering apparatus for aircraft



March 7, 1933. w. MOLLER 1,900,516

STEERING' APPARATUS FOR AIRCRAFT Filed June 18, 1931 2 Sheets-Sheet 1 March 7, 1933.

w. MULLER STEERING APPARATUS FOR AIRCRAFT 2 Sheets-Sheet 2 Filed June 18 1931 Patented Mar. 7, 1933 UNITED STATES PATENT OFFICE mammums 1 comm-non or arm!!! m, Gm, 8810303 1'0 OI m-FBIIDEIAU, emm, A

G mmm 103 mm Application fled June 18, 1931, Serial I0. I, and in Great Britain July 1, man.

This invention relates to steering apparatus for aircraft.

The present invention has for its object among other things to improve the construction disclosed and claimed in United States Letters Patent No. 1,729,850 of Oct. 1, 1929, and more particularly in United States Letters Patent No. 1,795,694 of March 10, 1931.

The above-mentioned United States Letters Patent No. 1,729,850 has essentially for 'its object to provide steering mechanism for aircraft enabling the passenger to determine the direction of travel by rotating a compass casing with respectto the magnet system thereof so as to control a source of power which supplies the forces for operating the lateral steering device, more specifically the rudder. According to said patent the source of power is provided by pressure of one or more jets or streams of a fluid, preferably-air, and which are controlled by the rotation im arted to the compass casing relatively to t e magnet system thereof. The apparatus may he used for setting a direction indicator which informs the pilot in which direction he has to steer as well as for effecting the steering automatically.

In the above-mentioned Letters Patent No. 1795,694, there is disclosed apparatus for effecting steering, and more particularly automatic steering of aircraft in which rotation of a com ass casing relative to the magnet system 0 said compass brings into operation a force or system of forces to operate the lateral steering means, more specifically the rudder of the aircraft, means responsive to turning movements of the aircraft being provided tending to 0p e the afore-mentioned force or system 0 forces.

In said patent relative movement of the compass magnet system and casing causes a fluid pressure difference which acts upon one or more membranes or pistons causing deflection or movement thereof and this deflection. or movement is communicated through suitable link and lever mechanism to a pivoted pressure fluid nozzle, the pressure fluid jet from which is divided more or [as equally according to the position of said nozzle between passages communicating with the opposite sides of a piston of a servo-motor w ich controls the rudder or other lateral steering means. The means responsive to turning movement of the aircraft are connected to a suitable movable pivot in the link and lever mechanism.

The present invention comprises an improvement in the invention disclosed in said Patent No. 1,795,694 in accordance with which the membrane or membranes is/are connected directly or through a resilient connection only with the pivoted pressure fluid nozzle or other controlling member.

The means responsive to turning movement of the aircraft, such as a gyrosco or turn indicator is also preferably connected directly or through a resilient connection with said nozzle, and the connection and arrangement are such that the recessional movements of the gyrosco or example tend to oppose the action 0 the compass on the lateral steering means.

In accordance with the resent invention means are also provided or returning the rudder to its central undeflected position at the completion of a turn.

Means are. also preferably provided for damping the precessional movements of the gyroscope or turn indicator, the reason for which will be described later.

Another improvement resides in the provision of means to counteract deviation from the true path of travel due to sideslip caused by lateral inclination of the aircraft.

Additional features of the present invention will be fully described in the course of this specification.

The invention and its aims and objects will he clearly understood from the following description, taken in connection with the accompanying drawings, of one embodiment of the invention herein given for illustrative urposes, the true scope of the invention in more fully pointed out in the appen ed claims.

In the drawings: Fig. 1 is a diagrammatic top view of the fuselage of an airplane illustrating certain features of the invention in part diagrammatically;

Fig. 2 is a lateral sectional elevation of an illustrative embodiment of the invention in which a controlling rela specifically a pressure fluid nozzle, is ad itionally influenced by means, such as a gyroscope, responsive to turning movements of the aircraft about its uprightaxis, and in which the gyroscope frame carries an adjustable weight, orts 22 and 24 being shown rotated throng 90 to bring them into the plane of the drawing for the sake of clearness;

Fig. 3 shows an illustrative embodiment of damping or power storage means;

Fig. 4 is a top plan view showing the relation of the fluid pressure nozzle with the piston servo-motor and means for returning the rudder to its central undeflected position; also the manner in which the source of power released by the compass is caused to act upon the nozzle. To simplify the drawings the rudder is shown as directly connected to the piston rod 16.

In the following description only so much of the earlier construction will be described as appears essential to the understanding of the present invention, reference being made to said above-referred to earlier patents for a more detailed descri tion of said earlier construction. It will understood however that the present invention is not to be considered as necessarily limited to said earlier construction.

The aircraft is steered on its course by lateral steering means, more specificall a vertical rudder 4, adjustment of said ru der being effected through lever 6, chain cables 8, and lever forming part of suitable operating mechanism herein illustratively comprising a-servo-motor consisting of a cylinder 14 in which works a piston 12 havin its piston rod 16 connected to the chain ca les 8. Pressure fluid, air, oil or the like, but

supplied to both sides of the piston 12 through passages 18 and 20 communicatin with ports 22 and 24 respectively, vid in a housing 23 located in front o be discharge opening of a nozzle 26, mounted to swing about the fulcrum 28 and from which there escapes a continuous jet of air under pressure. The air under pressure is continuously supplied to said nozzle through a conduit 80 b means of a blower 32 driven in any suita le manner by the aircraft engine 34. The nozzle 26 is connected to the center of a diaphragm 36 by a link 38, preferably with the interposition of a spring 89. 00 The two chambers 40 and 42 into which the interior of the dia hragm casing is divided by said diap ragm are supplled with air under pressure through conduits 46 and 48 from any suitable source, in the present as case most conveniently by a Ventun tube preferably compressed air, is continuously 50 suitably located upon the aircraft so as to be exposed to the rush of air produced by the aircraft travel. The ratio between the quantities of air pressure sup lied to said two chambers, that is to say t e pressure differential between the pressures existing upon opposite sides of the diaphragm is determined b suitable means operated by variation of t e relative position of the easing and magnet system of a compass 49. Said means may be similar to that described in said patents to which reference has been made.

So long as the aircraft follows the desired course and said course is not to be changed, so that the relative position of compass casing and magnet system remains unchan ed, the chambers 40, 42 will each be supp ied equally with com ressed air, so that equal pressure is exerte u on opposite sides of the diaphragm 36, an the nozzle 26 is maintained with its discharge opening in median position relative to the two ports 22 and 24. Said two ports are thus equally supplied with compressed air, there is equal pressure upon opposite sides of the piston 12 and said piston and consequently rudder 4 remain at rest. If, however, the aircraft deviates from the old course, either by reason of outside disturbances or influences or because by rotation of the compass casing 24 relative to its magnet system by the pilot the course of the aircraft is changed, then, owing to said rotation of the compass casing relatlve to its ma et system, the pressure ratio or ressure ifferential in the conduits 46, 48 wi be changed, higher pressure being thus exerted upon one side of the diaphragm 36 than upon the other. The diaphragm will therefore bulge to one side, the nozzle 26 will be dis aced from its median position and one o the rts 22, 24 will receive more compressed air than the other. The pressure differential thus created upon opposite sides of the piston 12 will move S81 lesser pressure. s movement, communicated to the rudder 4 through chain cables 8 and levers 6 and 10 will bring the aircraft back upon its old course or into the desired new course, as the case may be. This result will be obtained when the relative position of com ass casing and magnet system is again sue that the conduits 46 and 48 deliver the same amount of compressed air to o posite sides of the diaphragm 36, said diap agm and the nozzle 26 then returning to their original positions.

So far as I am aware, in all automatic steering apparatus for aircraft heretofore constructed, no account has been taken of the-influence resulting from the transverse inclination of the aircraft, althou h such influence may produce quite considerable deviations from the true or desired course TElston in the direction of of flight, and other disturbances. This influence results from the fact that upon each transverse inclination of an aircraft, that is to an at each deviation of the upright axis the total, lateral acceleration (the component of gravity and lateral acceleration) said aircraft begins to side-slip. Pressure commensurate with the speed of the side-slip is thus brought to bear upon the lateral steering means, more specificall the vertical rudder and other steering sur aces; said pressure-resultin in a turning movement of the aircraft w ch must be met by a greater or less adjustment of said lateral steering means.

In accordance with the present invention suitable means is provided to eliminate this source of error, resulting from the apparent transverse inclination of the aircraft. Preferably this is'accomplished by subjecting the automatic steering apparatus to the action of an additional ad usting or corrective force, which is dependent on the apparent transverse inclination of the aircraft, that is to say on. the position of lateral equilibrium of the aircraft with relation to the total lateral acceleration. Within the scope of the invention any suitable means may be used, but I have found suitable pendulous means to be the simplest solution and very satisfactory for the purpose. Said pendulous means will preferabl comprise a weight suitably disposed an arran d to pendulate in response to lateral inc ination of the aircraft. In the illustrative embodiment of the invention shown in Fig. 1 such a weight 52' is shown as conveniently aflixed to the controlling member or nozzle 26.

If for any cause the aircraft be thrown out of its position of lateral equilibrium the nozzle 26 will pendulate under the action of the weight 52 and its opening will therefore be displaced from its median position relative to the two ports 22 and 24, that is to say it will be displaced from its position as determined by the other controllin forces, whereby the amount of compresse air sup lied to ports 22 and 24 respectively, willie varied and an additional adjusting force, dependent on the lateral inclination of the aircraft, will be brought into action on the steering mechanism, herein the illustrative servo-motor 12-14 to act on the rudder2. It will be apparent that by suitably determining the weight 52 and its pendulous position on the nozzle 26, this additional adjusting force can be so regulated that any deviation from the true course, due to side-slip upon apparent lateral inclination of the aircraft, will corrected-in exactly the same manner as a pilot would correct it were manual steering used. In order that this re ation may be surely and easily accomplis ed or improved said we ht will preferably be adjustable longitudinally of the nozzle which may be accomplished in any well own conventional manner.

In accordance with the invention said amsm.

As willbe readily seen by reference to the above-referred to Patent No. 1,795,694,

forces additional to those exerted on the nozzle, by the compass for example, may be caused to act upon said nozzle, which additional forces may emanate from means responsive to turning-movement of the aircraft, said means comprising for example a precessing gyroscope having a precession axis parallel to its longitudinal axis, the object of said additional forces being to secure greater stability of steering free from disturbing pendulatlng motions.

If the automatic steering apparatus comprises such a stabilizing gyroscope, said gyroscope may serve to exert the correctional im ulse or force dependent on the apparent ateral inclination of the aircraft. This may be accomplished in various ways without de arting from the spirit of the invention; or example by locating the precessional axis of the gyroscope somewhat above the center of gravity of the gyroscope instead of causing it to pass through said center of gravity as is usually the case. I prefer, however, in this case also to use an adjustable weight as I have found that this arrangement makes possible a very fine adjustment of the additional force to be exerted by the weight, the weight being preferably adjustable. An illustrative convenient arran ement to this end is shown in Fig. 2, wherein the nozzle 26, mounted for swingingmovement at 53, is acted upon by a gyroscope having its rotor 54 mounted in the gyroscope frame 56 which is connected to said nozzle by a link 58 with or without the inter osition of a spring (not shown). The weig t 60 is herein ad ustably mounted upon the link 58. Upon apparent lateral inclination the weight 60 seeks to swing from its position and therefore to swing the nozzle 26 about its axis of rotation 53, thereby, through the connections already described, exerting the necessary correctional force on the rudder 4. An exact regulation may be secured b adjustment of the weight 60 longitudinal y of the link 58.

Referring more particularlyoto Fig. 2, the Igyrosco e exerts as in the a ve referred to atent 0. 1,795,694 an additional force upon the nozzle 26. The roscope rotor 54 may be conveniently driven by an air current or jet from a nozzle 62 acting on blades (not shown) of usual construction on the riphery of said rotor. The gyroscope ame 56, in which the roscope spindle 57 is rotatably mounted, is in turn rotatably mounted for precession about an axis parallel to the longitudinal axis of the aircraft, that is to say about pivots 64 journalled in the frame 66. The frame 56, as in said patent, transmits its precessional movements, caused by turning movement of the aircraft about its vertical axis, to the nozzle 26 but through resilient means instead of through the more com lex lever and link system of said patent. aid resilient means herein comprises sprin 68 attached at one end to said'nozzle an at their other ends to levers 70, 70 respectively, secured to the gyroscope frame 56 at opposite sides of said nozzle. By suitable adjustment of springs 68 and 39 relative to each other, the required adjustment or reg ulation of the compass action and of the counter action of the yl'oscope upon the nozzle 26 will. be secured, said gyroscope operating in such manner that b its action in opposition to the action oft e compass on the rudder it will prevent curves or tuming movements exceeding the limit of safety. On the other hand said gyroscope keeps the aircraft on a straight course in spite of other exterior disturbances causing sli ht pendulating motions.

he mode of operation is substantially the same as in said Patent No. 1,795,694, but the obnoxious lost motion due to the lever and link connections in said patent is avoided and the relative adjustment of the rudder and gyroscopic actions on each other is effected much more regularly and surely than was pomible by the adjustment of the various lever 'fulcrums necessary for this purpose in said patent.

As the nozzle 26 need make only a relatively sli ht swinging movement in order to reach e limit of its swinging'movement toward either side, that is to say, a osition in which one of the ports 22, 24 wil receive all of the compressed air or other fluid from said nozzle and the other none, so that further precession of the gyroscope would be without effect on the lateral steering means, the following objectionable results may occur in the case of undesired turning movements of the aircraft caused by heavy lateral gusts of wind for example.

It will be clear that the gyroscope is subjected to precessional force only so long as the turning movement of the aircraft continues, so that when, owing to the corrective action of the gyroscope on the lateral steering means, the turning movement ceases, the precesional forces acting on the gyroscope also cease. If the aircraft be now returned to its correct course by the corrective action of the rudder, the gyroscope will process in the opposite direction, thus tending to keep the aircraft on its deflected or wrong course, until by the con-' tinued action of the compass the action of the gyroscope is overcome and the aircraft is very gradually returned to the correct course. y repeated gusts of wind in quick succession the aircraft may therefore be deflectcd further and further from its true course before it can be restored to the correct course by the compass after each gust. Thus the automatic-steering apparatus may its function only too completely under conditions where repeated sts of wind act in succession upon one si e of the machine.

My invention contemplates the provision of means to prevent thls objectionable feature. I pre erably use for this purpose damping means or means for storing up the polglcessional energy. In the illustrative emment of the invention said damping means comprises a cylinder 72 (see 1*" s. 2 and 3) conveniently mounted atany suitable point, preferably on the frame 66 and in which works a piston 74 having its rod 76 pivotally connected. to a rod 73 carried a by the gyroscope frame 56. Adjacent the base of said cylinder there is provided a relative] minute opening 78 the size of which ma adjustable.

en the gyroscope frame 56 processes about its axis, said frame must act through the piston 74 to draw into the cylinder (2 or expel therefrom through said opening a quantlt of air commensurate with the extent o the precessional movement. The quantity of air drawn in or expelled is however, pro ortional to the product of the turning s ed of the aircraft and the time required or such movement, since the precessional force is substantially proportional to the turning speed of the aircraft. The gyroscope therefore yields gradually to the precessional action during the entire turning movement until, at the conclusion of said turning movement it comes to rest with a maximum precessional movement dependent on the turning 3 ed and the magnitude of the turning anglia in which the rudder is swung into a corresponding position to effect corrective steering. When the turning movement caused by a gust of wind has come to an end on account of corrective action by the rudder, the piston must suck in again or force out, through said minute opening, exactly the same amount of air before the roscope can return to its zero position. T e precessional energy of the gyroscope resulting from a more or less extended turn, and which would be lost once the nozzle has reached its extreme position, is therefore stored up by the c linder arrangement described. When t e turning posing the corrective action of the compass.

In accordance with the present invention, the return movement of the diverted rudder is also effected without the use of links or levers. This is conveniently accomplished W by making the frame 66 carrying the houssides of said piston respectively,

ing 33 containing the ports 22 and 24 rotatable about a stud shaft 80 in axial a ment with the axis 58 about which the nozzle 26 swings. Said frame 66 may he pgievided with a supporting roller 68 at its end adapted to run upon a suitabl curved rail 84. Connection with the rud der is conveniently effected by means of an arm 86 secured at one endto the frame 66 and having its other end forked-at 88 to be aged by a pin 90 carried by the piston 16 of theservo-motor. or cylinder 14. It will be apparent that every movement of the piston 12 and consequently of the rudder resulting from a 'deviation of. the nozzle'26 to one side or the other will correspondingly move the frame 66 through the connections above described with the result that the. two ports 22 and 24 will tend to assume such a position of rest that the discharge opening of the nozzle 26 will be between them. Thus every position of the rudder corresponds to a definite position of the nozzle 26 and vice versa.

It will be apparent that within the scope of the invention the means onsive to lateral inclination of the aircra such as the weight herein described or other pendulating means could act on the automatic, steering apparatus through separate mechanism a separate relay for example, in which case the re' ation'or adjustment could be effected y varying the action of the relay onthe servo-motor.-

I am aware that the invention ma be embodied in other specific forms wit out departing from the spirit or essential attri utes thereof; and therefore d 're the present embodiment to be conside in all s as illustrative and not restrictive,

reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

' I claim:

In Steering ap aratus foraircraft comprising, .in com ination, lateral steering means; pressure fluid driven operating mechanism therfor com a cylinder, a pistion in said cylin er, passages communicating with said cylinder on opposite and a nozzle to sup ly re'ssure fluid to sa' t pressure ui operated mechanism to mo c said nozzle relatively to passages supply pressure fluid t 661d" passages n o posite sides res P g M p s a varying ratio, and com risinga diaphra 1 chamber having a diap ragm connected @y a resilient connection to said nozzle, and p =l communicating with said diaphragm chamber at opposite sides respectively of said dia hragm; a compass having a relatively mova 1e magnet s stem and cas ing; and means, controlle by relative movement of the magnet s stem and casing, to direct the pressure flui in varying ratio into said last-named pas s.

2. Steering ap aratus' or aircraft comprising, in com ination, lateral steering means; pressure fluid driven operating mechanism therefor comprising a cylinder, a piston in said cylinder, passages communicating with said cylinder atvo posits sides of said piston respectively, an a nozzle to suppiypressure fluid to said passages; pressure uid operated mechanism to move said .nozzle relatively to said passages to supply pressure fluid to said passages in varying ratio and com rising a diaphragm chamber having a diap agm connected by a resilient connection to sai nozzle, and passages communicating with said diaph n chamber at tively of said diaving a relatively movmagnet and casing means controlled by relative movement of the magnet and casing to direct the pressure uid in varying ratio into said last-named p :n t; a ope mounted in a frame or recession about its axis responsive to 'movement of the aircraft about its verti axis; and a resilient connection between said pe frame and said nozzle, the precwsional movements of said roscope acting on said nozzle through sai resilient connection so as to tend to oppose the compass-controlled action of said diaphra on said nozzle. a y

3. tearing up aratus for aircraft comprising, .in com ination, lateral steering means; operating mechanism therefor; controlling means, com risin a resilient connection, for contro e o ration of said operating mechanism; an actuating means to actuate said controlling means for operating said lateral steering means.

4. Steering apparatus for aircraft comprising, in com ination, lateral steering means; operating mechanism therefor; contro means for contro the operation of said operating mechanism; actuating means to actuate said controlling means to operate said lateral steering means and means, onsive to turning movement of .the aircra about its vertical axis tending toactuate said controllin means in opposition to the action of said rat-named actuating means, said means responsive to turning movement of the aircraft hav ng a resilient connection with said controlling means.

5. apparatus for aircraft comprising, in combination lateral steering means; operating mechanism therefor;

means to ring into operation a force to actuate said operating mechanism; and means, comprising a resilient connection and responsive to turning movement of the aircraft about its vertical axis, to bring into operation a force tending to oppose the action of said first-named force.

6. Steering ap aratus for aircraft comprising, in com ination means; operating mechanism therefor; compass-governed controlling means acting on said operating mechanism through a resilient connection to steer the aircraft; a gyroscope mounted in a frame for precession about its axis res nsive to turnin' movement of the aircra about its vertica axis; and resilient connection between said gyroscope frame and said controlling the precessional movements of said gyroscope actin on said controlling means through sa' resilient connection so as to tend to oppose the action of said compass on said controlling means.

7. Steering apparatus for aircraft comprising,- in com ination, lateral steering means; operating mechanism therefor; a compass comprisin a relatively moveable magnet system an casing to actuate said operating mechanism to steer the aircraft; a gyroscope mounted in a frame for precession about its axis onsive to turning movement of the aircra about its vertical axis, to act upon said operating mechanism in opposition to the action thereon of said compass and damping means for, damping the precessional movements of said gyroscope, said damping means comprising a 40 piston connected to said gyroscope frame and working in a cylinder, meam being provided to allow slow passage of air into and out of said cylinder.

8. Steering ap 'aratus for aircraft com-' prising, in. com ination, lateral steering meazns; operating mechanism therefor; a

compass, comprising a relatively movable magnet system and casing, to actuate and operating mechanism to steer the aircraft; a roscope mounted in a frame for recession a b out its axis responsive to turning movement of the aircraft about its vertical axis, to act upon said steering meansoperating mechanism in opposition to the action thereon of said compass; and damping means for damping the precessional movements of said gyroscope.

9. Steering apparatus for aircraft comprising, in combination, lateral steering means: a steering servo-motor for actuating said lateral steering means; a source of power to furnish power to actuate said servo-motor; a relay to control said source of power; means responsive to lateral tum- .66 ing movem n of th ai c a t an Operativelateral steering means,

1y connected to said relay to operate said relay to actuate. said servo-motor; and operated by gravity means, operativ'ely connected to said rela and res nsive to turning movement of e aircra about its longitudinal axis to operate said relay to actuate said servo-motor.

10. Steeringv apparatus for aircraft comprising, in combination, lateral steering means; a steerin servo-motor operated by pressure fluid or actuating said lateral steering means; a movable nozzle to supply pressure fluid to said servo-motor to actuate the same; means res naive to lateral turning movement of ti? tively connected to said nozzle to move the same for actuaing said servo-motor; and operated by gravity means operatively connected to said nozzle and res nslve to turning movement of the aircra t about its power to actuate said servo-motor; a relay to control said source of powerm. gyroscope operatively connected to said relay to move the same to actuate said servo-motor upon precession of said gyroscope due to turmn movement of the aircraft about its vertica axis; and means connected to said gyroscope and to said relay and operated by gravity responsive to turning movement ofthe aircraft about its longitudinal axis, to, operate said relay to actuate said servo-motor.

12. Steering apparatus for aircraft comprising, in combination, lateral steering means; operating mechanism therefor; a compass comprising a relatively movable casing and magnet system; means actuated responsive to relative movement of said casing and magnet system to actuate said 0 crating mechanism; and means actuated, y

gravity responsive to lateral inclination of the aircraft to actuate said operating mechanism."

13. Steering apparatus for aircraft comprising, in combination, lateral steering means; operating mechanism therefor; means res onsive to turning movement of the aircra about its vertical axis to render said operating mechanism operative;'and means operated by gravity turning movement of said aircra about its longitudinal axis to render said operating mechanism operative.

-14. Steering apparatus for aircraft comprising, in combination, lateral steering means; operating mechanism therefor; means responsive to the turning movement of the aircraft about its vertical axis to render said operating mechanism operative; and pendulous means responsive to turning e aircraft and operanaive to a movement of said aircraft about its longi tudinal axis to render said operating mechanism operative.

15. Steering apparatus for aircraft, comprising in combination, lateral steering means; mechanism to operate said lateral steering means, said mechanism including a resilient connection; and means inr iding a resilient connection tending to oppose the operation of said lateral steering means by said operating mechanism.

16. Steering apparatus for aircraft, com prising in combination, lateral steering means; mechanism to operate said lateral steering means, said me ha m including a resilient connection; I .s, including a resilient connection, tending to oppose the operation of said lateral steering means by said operating mechanism; and means relatively to adjust the tension of said resilient connections.

17. Steering apparatus for aircraft, comprising in combination, lateral steering means; operating mechanism therefor; and

means, comprising a resilient connection,

automatically to actuate said operating mechanism responsive to turning mo ement of the aircraft about a vertical axis.

In testimony whereof, I have signed my name to this specification.

WALDEMAR MGLLE'R.

csnnncan: or connecnon.

Patent No. 1,900,5l6. March 7, 1933.

WALDEMAR MiiLLER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, line 48, claim 8, for "and" second occurrence read"said"; lines 67 and 68, claim 9, strike out thewords, "operated by gravity" and insert the same before"responsive" in line "69; line 82, claim 10, for "actuaing" read "actuating", and line 83, same claim, strike out the words "operated by gravity" and insert the same before "responsive" in line 84; and that the said Letters Harem should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 23rd day of May, A. D. 1933.

. M. J. Moore. (Seal) Acting Commissioner of Patents,

movement of said aircraft about its longi tudinal axis to render said operating mechanism operative.

15. Steering apparatus for aircraft, comprising in combination, lateral steering means; mechanism to operate said lateral steering means, said mechanism including a resilient connection; and means inr iding a resilient connection tending to oppose the operation of said lateral steering means by said operating mechanism.

16. Steering apparatus for aircraft, com prising in combination, lateral steering means; mechanism to operate said lateral steering means, said me ha m including a resilient connection; I .s, including a resilient connection, tending to oppose the operation of said lateral steering means by said operating mechanism; and means relatively to adjust the tension of said resilient connections.

17. Steering apparatus for aircraft, comprising in combination, lateral steering means; operating mechanism therefor; and

means, comprising a resilient connection,

automatically to actuate said operating mechanism responsive to turning mo ement of the aircraft about a vertical axis.

In testimony whereof, I have signed my name to this specification.

WALDEMAR MGLLE'R.

csnnncan: or connecnon.

Patent No. 1,900,5l6. March 7, 1933.

WALDEMAR MiiLLER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, line 48, claim 8, for "and" second occurrence read"said"; lines 67 and 68, claim 9, strike out thewords, "operated by gravity" and insert the same before"responsive" in line "69; line 82, claim 10, for "actuaing" read "actuating", and line 83, same claim, strike out the words "operated by gravity" and insert the same before "responsive" in line 84; and that the said Letters Belem should be read with these corrections therein that the same may conform to t'he i'ecord of the case in the Patent Office.

Signed and seared this 23rd day of May, A. D. 1933.

. M. J. Moore. (Seal) Acting Commissioner of Patents, 

